Existing 480V three phase three wire grounded "B" utility enters a 400 Amp fused service disconnect switch after the meter. "B" phase grounded at disconnect switch. 1/0 ground to water service and ground rods from disconnect. The three phase and one 1/0 ground equipment conductor enter a 400 Amp automatic transfer switch. Three phase conductors terminate on normal power position lugs of ATS. 1/0 ground equipment conductor placed on ATS enclosure lug for equipment ground. Existing 480V grounded "B" generator alternator failed and replaced with a 480V 3 phase, 4 wire WYE alternator by owner as a grounded "B" alternator is no longer available. Owner wants 480V 3 phase, 4 wire WYE on generator so if the utility service is replaced with a 480V 3 phase, 4 wire system in the future, the generator will also be 480V 3 phase, 4 wire and the system could be rewired. Existing outdoor generator has a 250 Amp circuit breaker with three 4/0 phase conductors running to the generator terminal lugs on the ATS. A #2 equipment ground conductor runs from the generator circuit breaker enclosure to the ATS enclosure equipment ground lug. Adding ground rods at the generator with a #2 ground conductor to generator circuit breaker enclosure equipment ground. Should the neutral connection on the new 480V 3 phase, 4 wire generator alternator be left floating (no connection) as it is not used (no line to neutral loads)? If left floating, the system is ungrounded and a ground detector would be installed. Essentially, when the ATS is in the normal position, the system is 480V grounded "B" three phase, three wire and when the ATS is in the generator position, the system is ungrounded 480V three phase, 3 wire.
480V grounded "B" service and 480V 3 phase 4 wire generator
- Thread starter TBP3643
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- Location
- Illinois
- Occupation
- retired electrician
Why not ground "B" phase from the generator for now, and remove that ground and ground the center of the wye when the service is changed from a grounded B phase to a wye later?
480V grouunded "b" service and 480V 3 phase 4 wire generator
480V grouunded "b" service and 480V 3 phase 4 wire generator
I was not aware that you could leave the neutral float and ground the "b" phase on a 480V three phase, four wire generator. If this is possible, the generator system would be safer grounded and the ground detection would not be needed.
480V grouunded "b" service and 480V 3 phase 4 wire generator
I was not aware that you could leave the neutral float and ground the "b" phase on a 480V three phase, four wire generator. If this is possible, the generator system would be safer grounded and the ground detection would not be needed.
- Location
- Illinois
- Occupation
- retired electrician
I am not completely sure about generators, but is not uncommon to do that with a transformer. I can't think of a reason why you can't do it with a generator.
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